Atlanta, Ga. From the Division of Plastic Surgery, Emory University.
Plast Reconstr Surg. 2012 Oct;130(4):793-800. doi: 10.1097/PRS.0b013e318262f174.
Capsular contracture has multiple causes, all of which lead to increased inflammation and scarring. There have been five generations of silicone breast implants; the most recent are filled with a highly cohesive gel thought to reduce capsular contracture. No independent data exist to support this claim.
Eight Göttingen swine were each implanted with eight 50-cc custom gel implants. In phase 1 of the study, the implant shells were photochemically altered to produce a low-bleed shell or a high-bleed shell to simulate a second-generation implant. In phase 2, both the third/fourth generation and the newest, fifth generation (highly cohesive gel) devices were implanted. Half the implants were punctured with a 3-ml punch biopsy to simulate a ruptured implant. Capsule and implant specimens were harvested at 1 and 3 months and analyzed with a Bose strain gauge. Intracapsular fluid was tested for silicon levels with atomic emission spectrometry. Histologic analysis was prepared with hematoxylin and eosin, Masson trichrome, and α-smooth muscle actin immunohistochemistry stains.
Gel bleed correlated with capsule stiffness in a dose-dependent manner (p < 0.05). High-bleed second-generation implants had the stiffest capsules, and nonruptured third- and fourth-generation implants had the softest. Histologic examination revealed an intermediate layer of spindle-like cells staining positive for α-smooth actin in the most contracted capsules.
There is a dose-dependant relationship between silicone gel bleed and capsule compliance that is independent of the cohesivity of the silicone. Capsule thickness and a fibrotic, α-smooth muscle actin-positive layer are present within the most contracted capsules.
包膜挛缩有多种原因，所有这些原因都会导致炎症和瘢痕形成增加。已经有五代硅胶乳房植入物；最新的是充满高粘性凝胶，据信可以减少包膜挛缩。没有独立的数据支持这一说法。
8 只哥廷根猪每只植入 8 个 50 立方厘米的定制凝胶植入物。在研究的第一阶段，通过光化学改变植入物外壳以产生低出血外壳或高出血外壳来模拟第二代植入物。在第二阶段，植入了第三代/第四代和最新的第五代（高粘性凝胶）设备。一半的植入物用 3 毫升的活检穿孔器刺穿，以模拟破裂的植入物。在 1 个月和 3 个月时收获包膜和植入物标本，并使用 Bose 应变计进行分析。用原子发射光谱法测试囊内液中的硅水平。用苏木精和伊红、马松三色和α-平滑肌肌动蛋白免疫组织化学染色制备组织学分析。
凝胶出血与囊的硬度呈剂量依赖性（p < 0.05）。高出血的第二代植入物具有最硬的包膜，而未破裂的第三代和第四代植入物具有最软的包膜。组织学检查显示，在最收缩的包膜中，存在一层阳性表达α-平滑肌肌动蛋白的纺锤形细胞中间层。
硅胶凝胶出血与包膜顺应性之间存在剂量依赖性关系，与硅胶的内聚性无关。在最收缩的包膜中，存在包膜厚度和纤维化的α-平滑肌肌动蛋白阳性层。
